var xhr = new XMLHttpRequest();
xhr.open("GET", `../php/index.php?hide=getcontent&id=${sessionStorage.id}`);
xhr.send(null);
xhr.onreadystatechange = () => {
    if (xhr.readyState == 4 && xhr.status == 200) {
        var data=JSON.parse(xhr.responseText);
        title.innerHTML=data.bookname;
        title.style.fontSize="30px";
        title.style.fontWeight="bold";
        title.style.textAlign="center";
        title.style.marginTop="30px"
        var arr=data.content.split(/\n/);
        arr.forEach(str=>{
            var p=document.createElement("p");
            p.innerHTML=str;
            p.style.textIndent="2em";
            p.style.lineHeight="50px";
            cont.appendChild(p);
        })
    }}